The present invention relates to a method for superimposing an image on a direct image of the surroundings in order to be displayed to an observer, the image which is to be superimposed being angled in towards the eye(s) of the observer from a different direction from the image of the surroundings and being generated starting from a line transmitter with image information which is two-dimensional in the time within the integration time of the eye and is converted into a two-dimensional image. The invention also relates to an arrangement for superimposing an image on a direct image of the surroundings in order to be displayed to the eyes of an observer, comprising a line transmitter for transmitting two-dimensional image information in linear form located in a different direction from the image of the surroundings, a converter for converting the image information in linear form into a two-dimensional image and a direction-changing means arranged so as to angle the radiation from the line transmitter in a direction towards the eyes of the observer.
A method and an arrangement according to the first paragraph are previously known from WO A2 9534014. This patent relates to an integrated spatially fixed display, in which the image content in a linear array is converted into a two-dimensional image in direct proximity to the linear array by means of a rotating mirror arrangement. In order to produce a large image, the arrangement has to be expanded in two dimensions.
This makes the arrangement bulky and difficult to position.
One object of the invention is to provide an arrangement which does not require the same space and is easier to position. The object of the invention is achieved by means of a method characterized in that the image information is converted into a two-dimensional image in proximity to the area in which the image is directed in towards the eyes of the observer, and an arrangement characterized in that the converter for converting the image information in linear form into a two-dimensional image is separate from the line transmitter and arranged in proximity to the direction-changing means. By means of the invention, which divides the display function into two separate parts, an arrangement is produced, which essentially expands in one dimension when the image is made larger.
An arrangement comprising a line transmitter with a separate converter is previously known from our patent EP 518 834. This document relates to a converter worn by the observer, the observer observing a linear display in his normal direction of vision. The present invention builds up the image displayed to the observer in a different manner by including the converter in proximity to the direction-changing means, where image information transmitted by the line transmitter is angled in towards the eye(s) of the observer and is superimposed on a direct image of the surroundings. Image superimposition in combination with a line transmitter with two-dimensional information affords great opportunities for compact designs, for example in vehicle applications.
The conversion of the image which is to be superimposed is carried out in equipment which is installed in a fixed manner relative to the line transmitter. Examples of converters are described in inter alia the EP document mentioned above and the patent SE 9503505-1. When use is made of equipment installed in a fixed manner, no equipment like spectacles worn by the observer is required, which should appeal to certain users.
The image which is to be superimposed on the direct image of the surroundings can also advantageously be an image of the surroundings obtained by means of, for example, an IR camera or some type of image intensifier. By combining the direct image with an IR image, markedly improved possibilities are afforded for driving in the dark and thus improved road safety. Alternatively, the image which is to be superimposed can be a synthesized image in the form of, for example, a map or symbols. In this way, it is made easier for the driver to handle the vehicle safely.
For converting the image information into a two-dimensional image, the converter consists, according to an advantageous embodiment in the case of fixed installation, of a deflector with deflection which is variable in time.
According to another advantageous embodiment, the direction-changing means consists of a mirror and a beam splitter in interaction.
According to a further advantageous embodiment, the beam splitter and the converter are arranged in an essentially common plane.
According to an expedient embodiment, when installed in a vehicle, the converter and the direction-changing means are arranged in proximity to the upper part of the front window of the vehicle, and the line transmitter is arranged, for example in proximity to the dashboard of the vehicle, so as to transmit in the direction towards the converter and the direction-changing means. In this connection, the converter and the direction-changing means are advantageously integrated with the sun visor of the vehicle. Installation in the above manner makes effective use of the spaces in a vehicle. Installation requires a minimum of space because an existing sun visor can be replaced by a modified sun visor with extended functioning, and the line transmitter can be arranged in the longitudinal direction of the dashboard.
According to an advantageous embodiment, in order to provide the line transmitter with image information, a camera, such as an IR camera or image intensifier, is arranged so as to transmit to the line transmitter the image information which is to be superimposed on the image of the surroundings. Alternatively, a sensor, such as a radar sensor or laser sensor, can be arranged so as to transmit to the line transmitter the image information which is to be superimposed on the image of the surroundings. It is common to all the camera and sensor variants that it is possible for the observer, usually the driver, to obtain valuable additional information which can make driving the vehicle easier.